NEFL and chronic obstructive pulmonary disease: These include blood volume and BMI, which are inversely related to NfL levels (Manouchehrinia et al., 2020); diabetes, COPD, cardiovascular disease, and COVID-19 infection, which are associated with increased NfL levels (Fitzgerald et al., 2022; Abdelhak et al., 2023); and pre-eclampsia and parturition, in which NfL levels are also elevated (Evers et al., 2018, 2019).